Use modes.SignatureHelp as source of truth for activeSignature

Use the model to track state and active parameter instead of tracking this in the widget itself. This enforces a cleaner boundary between model and view

This allows us to store additional data on the state, such as the active parameter

The parameter hints model can only be in a single state at a time. Use a single state variable to better track this

Code like:

```
private readonly _onDidEncounterLanguage: Emitter<LanguageId> = new Emitter<LanguageId>();
```

Does not need to repeat the `Emitter<LanguageId>` type annotation

Fixes #64724

Should prevent double dispatch of keyboard events in most cases

* Enable strict null checking for quickOpenScorer test

* Changing as any to Exclamation mark

Detect menu items invoked via keybinding and dispatch keybinding on renderer

* Enable strict null checking for Notirications test

* Changing as any to Exclamation mark